1. Science Embryology: Lesson 5: Egg Size and Grade Materials needed:
Each student needs:
-science binder with embryology packet
-highlighter
-set of egg from farm to store labels
-Eggs-tra Time packet

2. What are the two types of chickens and the differences between them?
The BIG Question:
What are the two types of chickens and the differences between them?
Last time, we learned the answer to this big question.
Can someone remind us?
What is one type of chicken?
What is that type of chicken raised for?
What is the other type of chicken?
We already learned how broiler chickens get from the farm to the grocery store, now let’s find out what happens to the eggs.
Here is our first big question for today…

3. How do eggs get from the farm to the grocery store?
The BIG Question:
How do eggs get from the farm to the grocery store?
Can someone read it for us?

4. To start you thinking, I am going to give you some labels
To start you thinking, I am going to give you some labels. You will also need to find page 31 in your binder. It should look like this.
You are going to cut apart your labels and put them in the order you think would show how the egg gets from the farm to the grocery store.
Then you’re going to do some reading to see if you were correct.
When you’re done reading, you’ll have some time to go back and rearrange your labels.
So, here are your things to do…

5. Things to do: Cut apart your labels and arrange them in
order on your sheet. Don’t peel off the back
yet!
Read about how the egg gets from the
farm to the store on pages in your
binder.
Can someone read * number 1?
Can someone read * number 2?
Can someone read * number 3?
Can someone read * number 4?
(Give time for students to complete the list with partners)
So, our big question was…
Check your labels. Rearrange them if
needed. Don’t peel off the back yet!
4. Work on your Eggs-tra Time Packet.

6. How do eggs get from the farm to the grocery store?
The BIG Question:
How do eggs get from the farm to the grocery store?
Let’s see what you found out.

7. Eggs are given a grade based on how fresh they are on the inside.
The conveyor belt moves the eggs to a machine that washes and dries them.
The eggs roll out of the hens’ cages onto a conveyor belt.
The eggs are passed over a bright light to check if the shells are cracked or if there is something wrong inside of them. This process is called candling.
Eggs are given a grade based on how fresh they are on the inside.
What happens first? *
What happens next? *
(do all 6 events)
You may peel off the backs and attach your labels.
A machine weighs the eggs and sorts them by size. They are then packaged into cartons.
The cartons of eggs are shipped to the supermarket in refrigerator trucks.

8. I have a short video clip to show you about how eggs get from the farm to the store.
(show video clip – Lesson 5: eggs from farm to you – about 1 minute)
Now let’s take some time to investigate this last big question…

9. How are eggs classified (sorted)?
The BIG Question:
How are eggs classified (sorted)?
Can someone read it?

10. Take a look at these eggs.
How might we sort them? (by color, by size)
Eggs of the same color are packaged together in cartons.
Let’s find out more about how eggs are sorted by size.
Find page 32 in your binder about egg size.

11. KNOW YOUR EGGS
Eggs are sold at the supermarket by size and grade. The egg size is the weight
of a dozen eggs. The egg grade is how fresh the egg is inside.
EGG SIZE
There are six different classes of egg weights: jumbo, extra large, large,
medium, small, and peewee. In the supermarket, you will see only four of these
classes; the jumbo and peewee sizes are almost never seen. This is because
layer hens seldom lay eggs of the jumbo or peewee sizes.
Can someone read the section called Know Your Eggs?
Let’s highlight two important definitions in this section…* *
Can someone read the section called Egg Size?
Let’s highlight the six sizes of eggs…*

12. Egg size is the weight of a dozen eggs.
It is important to remember that egg size is determined by the weight of the eggs.
And remember that it is not the weight of one egg that determines the size.
It is the weight of how many eggs? *
At the bottom of your page, you can see * the weights of each size of egg.
Do you notice a pattern in the weights? (increases by 3 oz.)

13. Here is a picture showing all six sizes of eggs.
Hens lay different size eggs depending on their age.
Younger hens lay smaller eggs.
The type of breed and the type of food the hen eats can also play a role in the size of the egg she will lay.

14. 3 Most Common Egg Sizes
The most common sizes of eggs you’ll see at the grocery store are medium, large, and extra large.
Besides size, our page mentioned that eggs are also sorted by something else.
What else are eggs sorted by? (grade)
Let’s find out more about egg grade. Take a look at the next page in your binder.

15. EGG GRADE Can someone read the first paragraph about egg grade?
The egg grade tells how fresh the egg is on the inside. There are only three grades of
eggs. They are the AA, A, and B. The AA grade eggs are the freshest, and the B grade
eggs are the least fresh, and the A grade eggs are somewhere between the AA and B
grades. Most of the eggs in the supermarket are Grade AA or A because they are very
fresh. They arrive at the supermarket within 1 or 2 days after they are laid.
Can someone read the first paragraph about egg grade?
Let’s highlight some important information.
* * * *
The egg grade is always marked somewhere on the carton of eggs…*

16. Three Grades of Eggs Grade AA Grade Grade B A
Let’s find out about the difference between the three egg grades at the bottom of our sheet.
(read AA)
Here is another picture of a grade AA egg. *
Look how thick and high the thick albumen is, especially from the side.
(read A)
Here is another picture of a grade A egg. *
The thick albumen is more spread out. It is not as thick.
(read B)
Here is another picture of a grade B egg. *
Look how spread out the thick albumen is and how thin it looks from the side.
Grade B
Grade A

17. Grade AA
Grade A
Grade B
Obviously the eggs can’t be broken open before you buy them, so egg grade is determined by candling the eggs.
Here is what you would see if you candled the three different grades.
In the AA egg, you can barely see the yolk because the albumen is so thick.
In Grade A, you can see more of the yolk; the albumen is not as thick.
In Grade B, you can really see the yolk; the albumen is much thinner.
Candlers also look at the air cell. Let me outline the air cells * because they are hard to see. The fresher the egg, the smaller the air cell.
One last thing that is considered for grading is the shell. * Look at the grade B shell. It is very irregular. A grade B shell might also be slightly stained, rather than clean white.

18. Science
Flash
Cards
Now we can fill in our last three flash cards.

19. 33 - egg grade 34 – A and AA 35 – one dozen (12) * 33 * 34 * 35
To finish off our unit, there are some interesting facts for us to read about chickens.
Before we read the first fact, think about this…

20. The average American eats about 37 pounds of chicken a year.
Which statement
is true?
The average American eats about 37 pounds of chicken a year.
The average American eats about 10 pounds of chicken a year.
(have students stand or use a show of hands to show which they think is true)
Let’s find out which is correct. Find page 34 in your binder called Chicken Facts.
(read first section)
Now think about this…

21. A hen lays about 100 eggs every year.
Which statement
is true?
A hen lays about 100 eggs every year.
A hen lays about 240 eggs a year.
(have students stand or use a show of hands to show which they think is true)
Let’s find out who’s correct. (read 2nd section)
Now think about this…

22. Chickens are very smart. Chicken are not very smart.
Which statement
is true?
Chickens are very smart.
Chicken are not very smart.
(have students stand or use a show of hands to show which they think is true)
Let’s find out who’s correct. (read 3rd section)
Let’s read the next sections to see why people say “You’re a chicken.”
Now think about this…

23. There are more chickens in the world than people.
Which statement
is true?
There are more chickens in the world than people.
There are more people in the world than chickens.
(have students stand or use a show of hands to show which they think is true)
Let’s find out who’s correct. (read 1st section on next page)
The last section is something we already know about. Can someone read that section?
I have one more interesting egg related fact for you to think about…

24. The largest bird egg is an ostrich egg.
Which statement
is true?
The largest bird egg is an ostrich egg.
The largest bird egg is a flamingo egg.
(have students stand or use a show of hands to show which they think is true)
And the answer is…

25. The ostrich lays the largest egg!
Here you can see an ostrich egg next to chicken eggs.
An ostrich egg can be 8 inches tall and weigh 3 pounds!